High water table means sump pump needed for family room

Q. I read your column every week and consider your opinion among the most expert and most useful I have come across. My problem is that after heavy and constant rainfall, usually in the spring, water seeps from the floor into the family room. The water starts to come in at the end of the family room facing the front lawn and in other areas the heavier the rain gets. I often get as much as an inch of water or more. My home is a high ranch -- built at the top of a small hill during the 1960s -- with a family room and a two-car garage in the lower portion of the house. The garage never gets flooded.

I repositioned the leaders to drain 10 feet away from the house and pitched the ground outside the house, facing the front lawn, to carry water away from the structure. My front lawn and driveway slope downward while my back lawn and property line are flat. The property line is over 10 feet from the family-room end of the house and is about 1 foot higher than my neighbor's property, so, when it rains, it collects a lot of water from his backyard and funnels it across the back of his property and into the street. The water in this area sometimes pools up for long periods and eventually soaks into the ground. There also is an underground PVC pipe that runs on my property along the property line and empties into the street. However, I checked it during a heavy rainfall, and it seems ineffective because it spills out very little water. I also checked to make sure the pipe was clear with a snake. Can you tell me more about this pipe?

Other than fixing the gutters and leaders and making sure the ground slopes away from the house, I have not done anything further to correct this problem. Contractors have recommended that I put in sump pumps with connecting channels inside the room, but I do not want them. French drains located outside the house also were recommended, but they are expensive. We were told that we have a high water table, so we think that this might be part of the problem. What are your thoughts and recommendations to fix this problem?

Pearl River, N.Y.

A. Because you have sloped the grade away from the house and extended the discharge of your downspouts (and you are on top of a small hill), it does seem that the water problem you are experiencing is caused by a high water table. Assuming that the concrete slab was poured over a stone bed 4 to 6 inches deep, the simplest solution is to have a sump pump installed close to the area where the water comes in. It will capture the water that fills the stone bed and keep it from building the pressure that causes the water to seep into the family room. I understand your reluctance to having such a set up installed, but it will be more reliable and a lot less expensive than a French drain.

A French drain will need to be installed below the footing of the house -- probably around the entire house -- and needs gravity for it to work, which means that its outlet needs to be higher than the street. And there's no guarantee that it will not eventually silt up or that it can handle the volume of water or relieve the pressure under the slab. French drains are best suited to capture water running down a hill behind a house before it gets to the foundation. On the other hand, a high-capacity submersible sump pump is more likely to keep the water level below the family-room floor.

For aesthetics, you may want to build a closet or other enclosure around it so it will not stare you in the face. If placed judiciously with the right output, you should not need the channels that have been suggested. This has worked in many similar situations. Be sure that you have the type of sump that I have described a number of times in this column. A bucket with holes will not cut the mustard: The sump needs to allow a free flow of water into it. Because I do not have the space to describe it here for you, I am sending you a reprint of my suggestion. Best of luck, and let me know whether it solves your problem. The buried PVC pipe was probably installed to carry the water that pools between your property and your neighbors. It may have silted by now, rendering it ineffective.

Q. I am contemplating a renovation of a ranch-style home that was built in South Jersey on a lagoon in 1978. The area in question is a crawl space. The crawl space is 9 to 10 inches below the exterior grade. I would like to remove the current kraft-faced batt insulation, which is installed with the kraft face on the crawl-space side of the floor, and have the entire floor sprayed with an expanded foam insulation to fill the area between the 2-by-10-inch floor joist. Because no vapor barrier exists on the warm side of the floor, I am hoping that the spray insulation will act as a vapor barrier as well.

The current crawl space is exposed sand. Due to water permeating the crawl space during high tide in northeast storms, I also am thinking of adding sand and/or gravel to raise the crawl-space level higher than the exterior grade. Should I add a 5-mil plastic vapor barrier as well on top of the gravel? Vents at 8 by 16 L are installed in the block perimeter walls.

I would appreciate your advice as to which of the spray/expanding foam insulations are the way to go for this project. I would like to thank you for your review of this condition.

Via e-mail

A. Have you made sure the floor joists and floor sheathing are OK? The situation you describe is conducive to the development of rot, as the insulation's kraft paper vapor retarder can seal any bypassing moisture in the joist cavities. I assume from your description that the water gets in your crawlspace through the walls during high tides.

In that case, raising the level of the crawlspace sand to above the exterior grade makes some sense. You have not said what the height of the crawlspace is, but if it is high enough for people to work in, and if a concrete truck can drive close enough to the house, you can have a pea-gravel slurry poured through the vents. You will need several people in the crawlspace with rakes and shovels to spread the slurry. But it will be a lot easier and faster, albeit more expensive, to have a concrete pumper shoot the slurry through the various vents. You will need to cover the stones with 6-mil plastic to keep the moisture from evaporating and creating a potential problem with the floor above.

If there is not enough space to accomplish this option, your other choice is to simply follow the suggestions below and save yourself a lot of work: Cover the sand with 6-mil plastic, making sure that the plastic is applied to the walls of the crawlspace a few inches above the level of the exterior grade. Tape it to clean surfaces.

But first, shape the sand to create a low spot in the center of the crawlspace with all sides flowing toward it, so if any water gets on top of the plastic, it can drain through a hole in the plastic (approximately 6 inches in diameter) to the sand below. But why go to the expense of replacing the fiberglass insulation with foam? You could simply turn the fiberglass insulation over, pushing the kraft paper vapor retarder against the subfloor above, and holding the insulation in place using "tiger's teeth" -- thin wires with pointed ends that are pushed in place and bite into the wood joists.

If you insist on foaming, check the condition of the joists to make sure they have not suffered from the existing conditions and, if all is well, use closed-cell polyurethane and have the foamers apply a thin coat of foam over the entire joists to insulate them from any moisture emanating from the soil.

Q. I am not sure which professional to consult regarding the problem I am experiencing and thought you could help me. I would appreciate any advice, as I learn a lot from your column and have avoided many mistakes as a result.

I live in a split-level. The lowest basement is completely underground, and the level under the kitchen/living/dining room is about 6 feet under. The lowest basement is unfinished and has a French drain. There is some seepage into the space but it is negligible. The next lowest level has an unfinished utility room and a finished recreation room. The utility room has some moisture in the cinder blocks of one of the corners (no standing water so far), which I manage with a dehumidifier.

When I moved in, I removed the walls in the recreation room and replaced them, since the previous owner had used stucco over the entire space. I put up a vapor barrier and green board as a precaution without realizing that there had been previous water problems in the space. Seven years later, the wallboard is bubbling all along the baseboards on the front-facing wall, and the carpet is starting to mildew. I'm guessing that the soil is too dense and that it's holding the water against the foundation.

I was thinking that maybe if I excavated the front wall at least 6 feet and used some sort of porous stone, it would lead the water down and hopefully away from the wall. I have no idea if this would really work, as I am completely inexperienced in this area. I'm not even sure who to talk to -- an excavator, a waterproofing person, a general contractor? Hire a home inspector?

My fear is that anyone I hire is going to give me an answer that requires their services -- which may or may not be a good idea. I would appreciate any direction or advice you can give.

Mountainside, N.J.

A. The first thing I recommend is that you look at the grade around your house. Most basement or crawlspace leakage problems are caused by a flat or negative grade (soil sloping toward the foundation). It is essential that the grade slope away from the foundation so that water is directed away from the house. The downspouts should also be checked to make sure their discharge is flowing away from the house. This should solve your problem.

If you are not sure how to determine what to do, your best bet is to hire an independent and certified home inspector to advise you. He or she should not sell you any other services -- it's against the ethics of the profession; they should only offer suggestions for solving your problem. Look in your Yellow Pages under "Home & Building Inspection Services," and find a listing for ASHI (American Society of Home Inspectors) members or go online to www.ashi.org and follow the prompts to find someone local.

© 2008, United Feature Syndicate, Inc.